1. Field of the Invention
The present invention disclosed in the specification relates to a method of fabricating a semiconductor device having a wiring electrode comprising aluminum or including aluminum as a major component.
2. Description of the Related Art
In recent years, a necessity of fabricating several millions of large amount of semiconductor devices on one chip or on the same substrate has been enhanced with high density integration of device elements. The problem in fabricating large amounts of semiconductor devices is the fabrication yield and operational failure of semiconductor devices considerably lowers the fabrication yield. As one of major causes of operational failure of semiconductor device, contact failure is pointed out.
Contact failure is an operational failure caused when connection failure occurs at a portion of electrically connecting a wiring electrode and a semiconductor device (hereafter, referred to as a contact). Particularly, the contact failure poses a serious problem in view of enhanced necessity of making electrical connection via a slender perforation (contact hole) by the miniaturizing technology and the multi layer wiring technology.
The causes of contact failure are grossly classified into three. The first cause is that a conductive film forming a wiring electrode and a source/drain region (semiconductor film) or a lead out electrode (conductive film) are not brought into ohmic contact with each other. This is due to the fact that an insulating coating, for example, a metal oxide or the like is formed on a contact face.
The second cause is that the coverage of a conductive film forming a wiring electrode is poor and disconnection is caused in a contact hole. In this case, improvement must be achieved by film forming method or film forming condition of the wiring electrode.
Further, the third cause is disconnection of a wiring electrode caused by the sectional shape of a contact hole or the like. The sectional shape of a contact hole is strongly dependent on etching conditions of an insulating material (SiN, SiO2, organic resin film or the like) covered on the contact portion.
Particularly, contact failure due to the second or the third cause is actualized with a higher aspect ratio of a contact hole by miniaturizing a semiconductor device.
It is an object of the present invention disclosed in the specification to reduce operational failure of a semiconductor device caused by contact failure by resolving the above-described problem. Particularly, it is an object of the present invention to provide the technology of eliminating contact failure when a material comprising aluminum or including aluminum as a major component is used as a wiring electrode.
Further, it is an object of the present invention to provide the technology of realizing a semiconductor device or an electro-optic device having high long period reliability by improving reliability of contact. Further, it is an object thereof to promote the yield of the fabrication steps.